In bi-directional communications systems of the related art, a ground station transmits and receives signals to and from a satellite, and the satellite, in turn, transmits and receives signals to and from a mobile platform. Typically, a plurality of satellites are present that cover particular geographic regions, and each satellite further includes a plurality of transponders that receive data from the ground station and subsequently transmit data to the mobile platform. In addition, the mobile platform includes receive and transmit antennas, which are used to communicate with the satellite transponders.
In order for the mobile platform to know which satellite transponders to communicate with, a series of forward link transponder assignments are either stored in receiver equipment on-board the mobile platform or transmitted to the mobile platform from the ground station. Generally, different transponders are used to transmit different types of services, i.e. video, audio, Internet, and others, and thus different forward link transponder assignments may be required for a mobile platform to receive the required data. Once the transponder assignments are known, the mobile platform then tunes its receivers to the correct transponder(s) according to the assignments, wherein a plurality of transponders may be tuned if a variety of data types are required by the mobile platform.
If the receiver equipment of the mobile platform fails, however, the mobile platform will lose its forward link transponder assignments and will not know which transponders to which its receivers must be tuned. As a result, the mobile platform loses its link with the specific satellite transponders, and further communications are disabled until the receiver equipment can be repaired or replaced.
Although a failure of the receiver equipment to link to a transponder results in a loss of data transmission, not all data transmissions are necessarily interrupted. Only the specific data or service type transmitted by the unlinked transponder is unavailable while other data types remain linked and available if the forward link assignments remain operational. However, while this data loss may only be partial, the overall effect on the mobile platform may be significant if one data or service type is dependent upon another, e.g. video and audio.
When a failure occurs in known art communications systems, the receiver equipment of the mobile platform is typically removed and replaced by maintenance personnel. Because the receiver equipment does not know the forward link transponder assignments for the specific mobile platform onto which it is installed, maintenance personnel may manually load the assignments during repair procedures. The manual loading of forward link transponder assignments requires additional manual operations and therefore increases aircraft downtime and maintenance costs. Moreover, the aircraft is generally on the ground during receiver equipment maintenance, and as a result, data communications from satellite transponders to the mobile platform are interrupted for the duration of the flight after which transponder links were lost.
Accordingly, there remains a need in the art for a communications system that can provide forward link transponder assignments to a mobile platform without the manual operations associated with receiver equipment maintenance, and which can provide the assignments during continued operation of the mobile platform.